[PATCH dtc] Implement the -R option and add a -S option.

[PATCH dtc] Implement the -R option and add a -S option.

[Jerry Van Baren]

Implement the -R <number> option to add memory reserve slots.
Add a -S <size> option makes the blob at least this number of bytes.

Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>
---
 dtc.c      |   19 ++++++++++++++++---
 dtc.h      |    6 ++++--
 flattree.c |   22 ++++++++++++++++++++--
 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/dtc.c b/dtc.c
index a009605..a94a402 100644
--- a/dtc.c
+++ b/dtc.c
@@ -21,6 +21,13 @@
 #include "dtc.h"
 #include "srcpos.h"
 
+/*
+ * Command line options
+ */
+int quiet;		/* Level of quietness */
+int reservenum;		/* Number of memory reservation slots */
+int minsize;		/* Minimum blob size */
+
 char *join_path(char *path, char *name)
 {
 	int lenp = strlen(path);
@@ -85,6 +92,8 @@ static void usage(void)
 	fprintf(stderr, "\t\tBlob version to produce, defaults to %d (relevant for dtb\n\t\tand asm output only)\n", OF_DEFAULT_VERSION);
 	fprintf(stderr, "\t-R <number>\n");
 	fprintf(stderr, "\t\tMake space for <number> reserve map entries (relevant for \n\t\tdtb and asm output only)\n");
+	fprintf(stderr, "\t-S <bytes>\n");
+	fprintf(stderr, "\t\tMake the blob at least <bytes> long (extra space)\n");
 	fprintf(stderr, "\t-b <number>\n");
 	fprintf(stderr, "\t\tSet the physical boot cpu\n");
 	fprintf(stderr, "\t-f\n");
@@ -104,12 +113,13 @@ int main(int argc, char *argv[])
 	FILE *inf = NULL;
 	FILE *outf = NULL;
 	int outversion = OF_DEFAULT_VERSION;
-	int reservenum = 1;
 	int boot_cpuid_phys = 0xfeedbeef;
 
-	quiet = 0;
+	quiet      = 0;
+	reservenum = 0;
+	minsize    = 0;
 
-	while ((opt = getopt(argc, argv, "hI:O:o:V:R:fqb:")) != EOF) {
+	while ((opt = getopt(argc, argv, "hI:O:o:V:R:S:fqb:")) != EOF) {
 		switch (opt) {
 		case 'I':
 			inform = optarg;
@@ -126,6 +136,9 @@ int main(int argc, char *argv[])
 		case 'R':
 			reservenum = strtol(optarg, NULL, 0);
 			break;
+		case 'S':
+			minsize = strtol(optarg, NULL, 0);
+			break;
 		case 'f':
 			force = 1;
 			break;
diff --git a/dtc.h b/dtc.h
index 7ed3df2..8cfe1a1 100644
--- a/dtc.h
+++ b/dtc.h
@@ -37,9 +37,11 @@
 #include "flat_dt.h"
 
 /*
- * Level of quietness
+ * Command line options
  */
-int quiet;
+extern int quiet;		/* Level of quietness */
+extern int reservenum;		/* Number of memory reservation slots */
+extern int minsize;		/* Minimum blob size */
 
 static inline void die(char * str, ...)
 {
diff --git a/flattree.c b/flattree.c
index 780142f..151d16e 100644
--- a/flattree.c
+++ b/flattree.c
@@ -295,10 +295,18 @@ static struct data flatten_reserve_list(struct reserve_info *reservelist,
 {
 	struct reserve_info *re;
 	struct data d = empty_data;
+	static struct reserve_entry null_re = {0,0};
+	int    j;
 
 	for (re = reservelist; re; re = re->next) {
 		d = data_append_re(d, &re->re);
 	}
+	/*
+	 * Add additional reserved slots if the user asked for them.
+	 */
+	for (j = 0; j < reservenum; j++) {
+		d = data_append_re(d, &null_re);
+	}
 	
 	return d;
 }
@@ -324,8 +332,18 @@ static void make_bph(struct boot_param_header *bph,
 	bph->off_dt_struct = cpu_to_be32(reserve_off + reservesize);
 	bph->off_dt_strings = cpu_to_be32(reserve_off + reservesize
 					  + dtsize);
-	bph->totalsize = cpu_to_be32(reserve_off + reservesize
-				     + dtsize + strsize);
+	bph->totalsize = reserve_off + reservesize + dtsize + strsize;
+	if (minsize > 0) {
+		if (bph->totalsize >= minsize) {
+			if (quiet < 1)
+				fprintf(stderr,
+					"Warning: blob size %d >= minimum size %d\n",
+					bph->totalsize, minsize);
+
+		} else
+			bph->totalsize = minsize;
+	}
+	bph->totalsize = cpu_to_be32(bph->totalsize);
 		
 	if (vi->flags & FTF_BOOTCPUID)
 		bph->boot_cpuid_phys = cpu_to_be32(boot_cpuid_phys);
-- 
1.4.4.4

Re: [PATCH dtc] Implement the -R option and add a -S option.

[Jon Loeliger]

So, like, the other day Jerry Van Baren mumbled:
> Implement the -R <number> option to add memory reserve slots.
> Add a -S <size> option makes the blob at least this number of bytes.
> 
> Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>

Applied.

Thanks,
jdl

Re: [PATCH dtc] Implement the -R option and add a -S option.

[Jerry Van Baren]

Jon Loeliger wrote:
> So, like, the other day Jerry Van Baren mumbled:
>> Implement the -R <number> option to add memory reserve slots.
>> Add a -S <size> option makes the blob at least this number of bytes.
>>
>> Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>
> 
> Applied.
> 
> Thanks,
> jdl

Thanks, Jon.  That makes the new u-boot "fdt" command tremendously 
easier to use because you can now allocate extra space in the blob at 
compile time rather than having to reallocate space using the u-boot 
"fdt" command.

Note to u-boot "fdt" command users:
* Pull the latest dtc source from Jon's repo
     <http://www.jdl.com/git_repos/>
* When you compile your dts, use the new -S parameter to create some
     extra space (e.g. -S 0x2000).  If you don't want to guess how big
     your current blob is, run a test compile with -S 1 - you will get
     a warning (don't use -q ;-) that will tell you how big your
     blob is.  Re-run with a reasonable -S.
* The -R to make extra mem reserve slots may be useful too.
* Make sure you *don't* specify version 16 (some legacy recipes do
     that).  The latest version is 17 and dtc now Does The Right Thing
     without needing the version specified.  Do *not* use -V.

Best regards,
gvb

Re: [PATCH dtc] Implement the -R option and add a -S option.

[Scott Wood]

On Wed, Apr 04, 2007 at 10:04:33PM -0400, Jerry Van Baren wrote:
> Implement the -R <number> option to add memory reserve slots.
> Add a -S <size> option makes the blob at least this number of bytes.

Wouldn't it be better to just specify the amount of extra space, instead
of the minimum total space?  That way, you only need to know what you
intend to add, not how much is already there.

-Scott

Re: [PATCH dtc] Implement the -R option and add a -S option.

[Jerry Van Baren]

Scott Wood wrote:
> On Wed, Apr 04, 2007 at 10:04:33PM -0400, Jerry Van Baren wrote:
>> Implement the -R <number> option to add memory reserve slots.
>> Add a -S <size> option makes the blob at least this number of bytes.
> 
> Wouldn't it be better to just specify the amount of extra space, instead
> of the minimum total space?  That way, you only need to know what you
> intend to add, not how much is already there.
> 
> -Scott

I thought briefly about this, but decided to implement a fixed size so 
that someone could allocate, say, 8K of memory in their memory map 
(likely flash) and know their blob would fit.

Maybe we need a little -s option to say "add -s bytes".

Jon suggested a --stats option to print out the important statistics. 
That would also be a good enhancement.

gvb

Re: [PATCH dtc] Implement the -R option and add a -S option.

[David Gibson]

On Thu, Apr 05, 2007 at 01:10:40PM -0400, Jerry Van Baren wrote:
> Scott Wood wrote:
> > On Wed, Apr 04, 2007 at 10:04:33PM -0400, Jerry Van Baren wrote:
> >> Implement the -R <number> option to add memory reserve slots.
> >> Add a -S <size> option makes the blob at least this number of bytes.
> > 
> > Wouldn't it be better to just specify the amount of extra space, instead
> > of the minimum total space?  That way, you only need to know what you
> > intend to add, not how much is already there.
> > 
> > -Scott
> 
> I thought briefly about this, but decided to implement a fixed size so 
> that someone could allocate, say, 8K of memory in their memory map 
> (likely flash) and know their blob would fit.
> 
> Maybe we need a little -s option to say "add -s bytes".

I think having both options would be a good idea.  It would also be
nice to have options to do this from the dts file (something similar
to /memreserve/).

> Jon suggested a --stats option to print out the important statistics. 
> That would also be a good enhancement.

Ok.  How would you envisage this working?

I've thought for some time that it would be a good idea to add an
"info" output mode.  In that mode instead of outputting a converted
device tree, it would give various bits of info on the input tree.
This would include things like the header field debugging information
that's currently output as pseudo-error messages when using dtb input.

I'm not sure to what extent your "--stats" idea would overlap with
that.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: [PATCH dtc] Implement the -R option and add a -S option.

[Jerry Van Baren]

David Gibson wrote:
> On Thu, Apr 05, 2007 at 01:10:40PM -0400, Jerry Van Baren wrote:
>> Scott Wood wrote:
>>> On Wed, Apr 04, 2007 at 10:04:33PM -0400, Jerry Van Baren wrote:
>>>> Implement the -R <number> option to add memory reserve slots.
>>>> Add a -S <size> option makes the blob at least this number of bytes.
>>> Wouldn't it be better to just specify the amount of extra space, instead
>>> of the minimum total space?  That way, you only need to know what you
>>> intend to add, not how much is already there.
>>>
>>> -Scott
>> I thought briefly about this, but decided to implement a fixed size so 
>> that someone could allocate, say, 8K of memory in their memory map 
>> (likely flash) and know their blob would fit.
>>
>> Maybe we need a little -s option to say "add -s bytes".
> 
> I think having both options would be a good idea.  It would also be
> nice to have options to do this from the dts file (something similar
> to /memreserve/).
> 
>> Jon suggested a --stats option to print out the important statistics. 
>> That would also be a good enhancement.
> 
> Ok.  How would you envisage this working?
> 
> I've thought for some time that it would be a good idea to add an
> "info" output mode.  In that mode instead of outputting a converted
> device tree, it would give various bits of info on the input tree.
> This would include things like the header field debugging information
> that's currently output as pseudo-error messages when using dtb input.
> 
> I'm not sure to what extent your "--stats" idea would overlap with
> that.

Hi David,

Well, that was Jon's suggestion/idea so I have not thought about it 
much.  It would probably overlap 100% with your --info idea, with the 
exception that Jon's suggestion would also put out the blob.

Since the dtc puts out the blob to sdtout, this actually is problematic. 
  I presume that is why you suggest inhibiting output.  Using stderr 
would sorta bypass that problem, but is not ideal (IMHO).

Is there any reason we don't have a -o option to direct the compiled 
blob output to a file?  Since the usual use is to write to a file, it 
would free up stdout for (info/stats) outputs.

On an unrelated related note, I don't believe my -R additions are 
actually putting out additional reserve map slots (easiest to see using 
the asm format output).  I'm still trying to understand why not, it 
seemed pretty straight-forward.  When I implemented it, I was looking at 
hexdumps of the dtb binary format and looking at the header and thought 
I had it working... using it with my u-boot mods shows no extra reserved 
slots.  I'm looking into where I went wrong.

Best regards,
gvb

Re: [PATCH dtc] Implement the -R option and add a -S option.

[Jerry Van Baren]

Jerry Van Baren wrote:

[snip]

> On an unrelated related note, I don't believe my -R additions are 
> actually putting out additional reserve map slots (easiest to see using 
> the asm format output).  I'm still trying to understand why not, it 
> seemed pretty straight-forward.  When I implemented it, I was looking at 
> hexdumps of the dtb binary format and looking at the header and thought 
> I had it working... using it with my u-boot mods shows no extra reserved 
> slots.  I'm looking into where I went wrong.

OK, I didn't add a reserve additional slots output in the asm emission 
code, so that was a pretty simple fix.  I'll provide a patch after a bit 
more testing.

gvb

Re: [PATCH dtc] Implement the -R option and add a -S option.

[David Gibson]

On Sat, Apr 14, 2007 at 08:58:49AM -0400, Jerry Van Baren wrote:
> David Gibson wrote:
> > On Thu, Apr 05, 2007 at 01:10:40PM -0400, Jerry Van Baren wrote:
> >> Scott Wood wrote:
> >>> On Wed, Apr 04, 2007 at 10:04:33PM -0400, Jerry Van Baren wrote:
> >>>> Implement the -R <number> option to add memory reserve slots.
> >>>> Add a -S <size> option makes the blob at least this number of bytes.
> >>> Wouldn't it be better to just specify the amount of extra space, instead
> >>> of the minimum total space?  That way, you only need to know what you
> >>> intend to add, not how much is already there.
> >>>
> >>> -Scott
> >> I thought briefly about this, but decided to implement a fixed size so 
> >> that someone could allocate, say, 8K of memory in their memory map 
> >> (likely flash) and know their blob would fit.
> >>
> >> Maybe we need a little -s option to say "add -s bytes".
> > 
> > I think having both options would be a good idea.  It would also be
> > nice to have options to do this from the dts file (something similar
> > to /memreserve/).
> > 
> >> Jon suggested a --stats option to print out the important statistics. 
> >> That would also be a good enhancement.
> > 
> > Ok.  How would you envisage this working?
> > 
> > I've thought for some time that it would be a good idea to add an
> > "info" output mode.  In that mode instead of outputting a converted
> > device tree, it would give various bits of info on the input tree.
> > This would include things like the header field debugging information
> > that's currently output as pseudo-error messages when using dtb input.
> > 
> > I'm not sure to what extent your "--stats" idea would overlap with
> > that.
> 
> Hi David,
> 
> Well, that was Jon's suggestion/idea so I have not thought about it 
> much.  It would probably overlap 100% with your --info idea, with the 
> exception that Jon's suggestion would also put out the blob.

Well, my idea wasn't a new --info but rather "-O info", if that
distinction makes sense.

> Since the dtc puts out the blob to sdtout, this actually is problematic. 
>   I presume that is why you suggest inhibiting output.  Using stderr 
> would sorta bypass that problem, but is not ideal (IMHO).

Yes, that's more or less precisely my reasoning.

> Is there any reason we don't have a -o option to direct the compiled 
> blob output to a file?  Since the usual use is to write to a file, it 
> would free up stdout for (info/stats) outputs.

We do have a -o option...

> On an unrelated related note, I don't believe my -R additions are 
> actually putting out additional reserve map slots (easiest to see using 
> the asm format output).  I'm still trying to understand why not, it 
> seemed pretty straight-forward.  When I implemented it, I was looking at 
> hexdumps of the dtb binary format and looking at the header and thought 
> I had it working... using it with my u-boot mods shows no extra reserved 
> slots.  I'm looking into where I went wrong.

Be careful to check the actual offsets.  Bear in mind that objdump may
elide zero words.  Also bear in mind that the only way a reader of the
device tree has of counting the number of reserve entries is stepping
through until it hits the terminating (0,0), so the extra entries will
just look like an early termination of the list.  In this sense -R
doesn't add "extra slots", but just ensures that there is space after
the reserve map to add more entries.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: [PATCH dtc] Implement the -R option and add a -S option.

[Jerry Van Baren]

David Gibson wrote:
> On Sat, Apr 14, 2007 at 08:58:49AM -0400, Jerry Van Baren wrote:

[snip]

>> On an unrelated related note, I don't believe my -R additions are 
>> actually putting out additional reserve map slots (easiest to see using 
>> the asm format output).  I'm still trying to understand why not, it 
>> seemed pretty straight-forward.  When I implemented it, I was looking at 
>> hexdumps of the dtb binary format and looking at the header and thought 
>> I had it working... using it with my u-boot mods shows no extra reserved 
>> slots.  I'm looking into where I went wrong.
> 
> Be careful to check the actual offsets.  Bear in mind that objdump may
> elide zero words.  Also bear in mind that the only way a reader of the
> device tree has of counting the number of reserve entries is stepping
> through until it hits the terminating (0,0), so the extra entries will
> just look like an early termination of the list.  In this sense -R
> doesn't add "extra slots", but just ensures that there is space after
> the reserve map to add more entries.

Hi David,

It actually is OK, went back and verified it.  I needed to modify the 
asm output to implement the -R extra slots which was confusing me (patch 
that you didn't like the calloc in ;-).

The calloc change was actually window dressing, I was just being 
paranoid about a binary blob that is bigger than its contents (has extra 
space).  The unused space is unused, so it doen't really matter if it is 
non-zero.  I'll roll a new version.

gvb

Re: [PATCH dtc] Implement the -R option and add a -S option.

[David Gibson]

On Sat, Apr 14, 2007 at 10:13:49PM -0400, Jerry Van Baren wrote:
> David Gibson wrote:
> > On Sat, Apr 14, 2007 at 08:58:49AM -0400, Jerry Van Baren wrote:
> 
> [snip]
> 
> >> On an unrelated related note, I don't believe my -R additions are 
> >> actually putting out additional reserve map slots (easiest to see using 
> >> the asm format output).  I'm still trying to understand why not, it 
> >> seemed pretty straight-forward.  When I implemented it, I was looking at 
> >> hexdumps of the dtb binary format and looking at the header and thought 
> >> I had it working... using it with my u-boot mods shows no extra reserved 
> >> slots.  I'm looking into where I went wrong.
> > 
> > Be careful to check the actual offsets.  Bear in mind that objdump may
> > elide zero words.  Also bear in mind that the only way a reader of the
> > device tree has of counting the number of reserve entries is stepping
> > through until it hits the terminating (0,0), so the extra entries will
> > just look like an early termination of the list.  In this sense -R
> > doesn't add "extra slots", but just ensures that there is space after
> > the reserve map to add more entries.
> 
> Hi David,
> 
> It actually is OK, went back and verified it.  I needed to modify the 
> asm output to implement the -R extra slots which was confusing me (patch 
> that you didn't like the calloc in ;-).
> 
> The calloc change was actually window dressing, I was just being 
> paranoid about a binary blob that is bigger than its contents (has extra 
> space).  The unused space is unused, so it doen't really matter if it is 
> non-zero.  I'll roll a new version.

Oh, I think zeroing it is correct, I'd just prefer it was done at the
callsite, rather than within xmalloc().  Strictly speaking you're
right, what's in the extra area shouldn't matter, but I don't like the
idea of potentially leaking random memory contents to file, which I
think could happen without a memset().  Because dtc is unpriveleged it
shouldn't actually matter, but it's ugly and a bad habit to establish.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: [PATCH dtc] Implement the -R option and add a -S option.

[Jerry Van Baren]

David Gibson wrote:
> On Sat, Apr 14, 2007 at 10:13:49PM -0400, Jerry Van Baren wrote:
>> David Gibson wrote:
>>> On Sat, Apr 14, 2007 at 08:58:49AM -0400, Jerry Van Baren wrote:
>> [snip]
>>
>>>> On an unrelated related note, I don't believe my -R additions are 
>>>> actually putting out additional reserve map slots (easiest to see using 
>>>> the asm format output).  I'm still trying to understand why not, it 
>>>> seemed pretty straight-forward.  When I implemented it, I was looking at 
>>>> hexdumps of the dtb binary format and looking at the header and thought 
>>>> I had it working... using it with my u-boot mods shows no extra reserved 
>>>> slots.  I'm looking into where I went wrong.
>>> Be careful to check the actual offsets.  Bear in mind that objdump may
>>> elide zero words.  Also bear in mind that the only way a reader of the
>>> device tree has of counting the number of reserve entries is stepping
>>> through until it hits the terminating (0,0), so the extra entries will
>>> just look like an early termination of the list.  In this sense -R
>>> doesn't add "extra slots", but just ensures that there is space after
>>> the reserve map to add more entries.
>> Hi David,
>>
>> It actually is OK, went back and verified it.  I needed to modify the 
>> asm output to implement the -R extra slots which was confusing me (patch 
>> that you didn't like the calloc in ;-).
>>
>> The calloc change was actually window dressing, I was just being 
>> paranoid about a binary blob that is bigger than its contents (has extra 
>> space).  The unused space is unused, so it doen't really matter if it is 
>> non-zero.  I'll roll a new version.
> 
> Oh, I think zeroing it is correct, I'd just prefer it was done at the
> callsite, rather than within xmalloc().  Strictly speaking you're
> right, what's in the extra area shouldn't matter, but I don't like the
> idea of potentially leaking random memory contents to file, which I
> think could happen without a memset().  Because dtc is unpriveleged it
> shouldn't actually matter, but it's ugly and a bad habit to establish.

Where I got concerned was a conversion of a .dtb input into a .dts or 
.asm output (or even a .dtb output).  I've run it and verified that the 
extra space (which is potentially random garbage) is not copied to the 
output - the size in the header is what it is and the data output is 
only the actual data (no major surprise there).

Generating a text output format actually strips the extra size/data 
because dtc turns it back into a symbolic form and padding is outside of 
the symbolic form, if you follow my drift (there isn't a way to 
represent extra blob padding in a dts format).

gvb

[PATCH: dtc] Implement the -R option and add a -S option.

[Jerry Van Baren]

Implement the -R <number> option to add memory reserve slots.
Add a -S <size> option makes the blob at least this number of bytes.

Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>
---
 dtc.c      |   19 ++++++++++++++++---
 dtc.h      |    6 ++++--
 flattree.c |   22 ++++++++++++++++++++--
 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/dtc.c b/dtc.c
index a009605..a94a402 100644
--- a/dtc.c
+++ b/dtc.c
@@ -21,6 +21,13 @@
 #include "dtc.h"
 #include "srcpos.h"
 
+/*
+ * Command line options
+ */
+int quiet;		/* Level of quietness */
+int reservenum;		/* Number of memory reservation slots */
+int minsize;		/* Minimum blob size */
+
 char *join_path(char *path, char *name)
 {
 	int lenp = strlen(path);
@@ -85,6 +92,8 @@ static void usage(void)
 	fprintf(stderr, "\t\tBlob version to produce, defaults to %d (relevant for dtb\n\t\tand asm output only)\n", OF_DEFAULT_VERSION);
 	fprintf(stderr, "\t-R <number>\n");
 	fprintf(stderr, "\t\tMake space for <number> reserve map entries (relevant for \n\t\tdtb and asm output only)\n");
+	fprintf(stderr, "\t-S <bytes>\n");
+	fprintf(stderr, "\t\tMake the blob at least <bytes> long (extra space)\n");
 	fprintf(stderr, "\t-b <number>\n");
 	fprintf(stderr, "\t\tSet the physical boot cpu\n");
 	fprintf(stderr, "\t-f\n");
@@ -104,12 +113,13 @@ int main(int argc, char *argv[])
 	FILE *inf = NULL;
 	FILE *outf = NULL;
 	int outversion = OF_DEFAULT_VERSION;
-	int reservenum = 1;
 	int boot_cpuid_phys = 0xfeedbeef;
 
-	quiet = 0;
+	quiet      = 0;
+	reservenum = 0;
+	minsize    = 0;
 
-	while ((opt = getopt(argc, argv, "hI:O:o:V:R:fqb:")) != EOF) {
+	while ((opt = getopt(argc, argv, "hI:O:o:V:R:S:fqb:")) != EOF) {
 		switch (opt) {
 		case 'I':
 			inform = optarg;
@@ -126,6 +136,9 @@ int main(int argc, char *argv[])
 		case 'R':
 			reservenum = strtol(optarg, NULL, 0);
 			break;
+		case 'S':
+			minsize = strtol(optarg, NULL, 0);
+			break;
 		case 'f':
 			force = 1;
 			break;
diff --git a/dtc.h b/dtc.h
index 7ed3df2..8cfe1a1 100644
--- a/dtc.h
+++ b/dtc.h
@@ -37,9 +37,11 @@
 #include "flat_dt.h"
 
 /*
- * Level of quietness
+ * Command line options
  */
-int quiet;
+extern int quiet;		/* Level of quietness */
+extern int reservenum;		/* Number of memory reservation slots */
+extern int minsize;		/* Minimum blob size */
 
 static inline void die(char * str, ...)
 {
diff --git a/flattree.c b/flattree.c
index 780142f..151d16e 100644
--- a/flattree.c
+++ b/flattree.c
@@ -295,10 +295,18 @@ static struct data flatten_reserve_list(struct reserve_info *reservelist,
 {
 	struct reserve_info *re;
 	struct data d = empty_data;
+	static struct reserve_entry null_re = {0,0};
+	int    j;
 
 	for (re = reservelist; re; re = re->next) {
 		d = data_append_re(d, &re->re);
 	}
+	/*
+	 * Add additional reserved slots if the user asked for them.
+	 */
+	for (j = 0; j < reservenum; j++) {
+		d = data_append_re(d, &null_re);
+	}
 	
 	return d;
 }
@@ -324,8 +332,18 @@ static void make_bph(struct boot_param_header *bph,
 	bph->off_dt_struct = cpu_to_be32(reserve_off + reservesize);
 	bph->off_dt_strings = cpu_to_be32(reserve_off + reservesize
 					  + dtsize);
-	bph->totalsize = cpu_to_be32(reserve_off + reservesize
-				     + dtsize + strsize);
+	bph->totalsize = reserve_off + reservesize + dtsize + strsize;
+	if (minsize > 0) {
+		if (bph->totalsize >= minsize) {
+			if (quiet < 1)
+				fprintf(stderr,
+					"Warning: blob size %d >= minimum size %d\n",
+					bph->totalsize, minsize);
+
+		} else
+			bph->totalsize = minsize;
+	}
+	bph->totalsize = cpu_to_be32(bph->totalsize);
 		
 	if (vi->flags & FTF_BOOTCPUID)
 		bph->boot_cpuid_phys = cpu_to_be32(boot_cpuid_phys);
-- 
1.4.4.4